The present invention relates to a method and apparatus for treating cigarette paper, imitation cork or other types of wrapping material for cigarettes or analogous rod-shaped articles which constitute or form part of smokers' products in a machine which manufactures or processes such products. More particularly, the invention relates to improvements in a method and apparatus for making holes in strips, webs or sheets of wrapping material for cigarettes, filter rod sections or like rod-shaped articles by resorting to a perforating device which is installed in a producing or processing machine and perforates the wrapping material by generating sparks between first and second electrodes. A perforating device which can be used to make holes in wrapping material for cigarettes or the like is disclosed, for example, in commonly owned copending patent application Ser. No. 003,364 filed Jan. 15, 1979 by Anton Baier, now U.S. Pat. No. 4,247,754 granted Jan. 27, 1981.
The purpose of making holes in the wrappers of cigarettes or like rod-shaped articles which constitute or form part of smokers' products is to allow penetration of a certain amount of atmospheric air into the column of tabacco smoke. It is believed that the admixture of fresh atmospheric air to tobacco smoke reduces the deleterious effects of nicotine and/or condensate. Perforating devices which are used to make holes in cigarette paper, artificial cork or like wrapping material can employ needles or analogous mechanical parts which simply penetrate through a running web or a finished wrapper without removing any material therefrom. It is also known to resort to laser beams which burn holes into the wrapping material as well as to employ sets of electrodes defining spark gaps through which the wrapping material is caused to pass whereby the sparks which jump across the gaps, when the electrodes receive high-voltage pulses from a suitable source, burn holes into the wrapping material. Such making of holes is accompanied by the development of dust particles, namely, fragments of wrapping material which must be removed from the spark gaps. Moreover, the formation of holes by resorting to spark gaps is accompanied by the development of substantial quantities of ozone which is detrimental to the health of attendants. Removal of ozone, prevention of development of appreciable quantities of ozone, as well as removal of particles of dust are desirable on the additional ground that this contributes to longer useful life of the electrodes. Therefore, the machine which embodies the perforating device need not be idled at frequent intervals for the sole purpose of inspecting, cleaning, repairing and/or replacing one or more electrodes. Each interruption of operation of a modern high-speed cigarette maker entails the loss of approximately 6000 cigarettes per minute so that the manufacturers of cigarettes are evidently interested in maintaining the machines in continuous operation during the entire shift and are even more interested in ensuring that the operation will not be interrupted on the sole ground that one or more electrodes of the perforating device (which, when compared with the cost of the entire machine, constitutes but a minor component of the cigarette maker) require inspection, repair or replacement.
The mounting of the perforating device directly in the machine which manufactures and/or processes cigarettes or other rod-shaped articles which constitute or form part of smokers' products is desirable and advantages because the operation of the perforating device can be regulated in immediate response to detection of rod-shaped articles with wrappers which exhibit excessive or insufficient permeability to the flow of air therethrough. Such immediate regulation would not be possible if the wrapping material were perforated at the plant where the wrapping material is made, i.e., at a locus which is remote from the machine for the making and/or processing of plain or filter tipped cigarettes, cheroots, cigarillos or cigars or filter rod sections.